Recently I found Firefox was crashing regularly. It crashed more often than Netscape or IE ever did. Then one time I finally found how to reproduce the crash. The link to one story on Reddit would always make Firefox hesitate and promptly crash. I first noticed this because the story was at the top of the Reddit home page. Fortunately, the crash also happened on the story's comments page, and so it didn't depend on the layout of the home page.
At first it seemed like a problem with Redirect Remover because that extension was active on the link, and its special cursor remained even after I moved it off the link. However, then I thought that it might be a conflict with another extension, and through a binary search I found that it was a conflict with Secure Login. In order for the crash to occur, both extensions needed to be enabled, the page couldn't be loaded from a local file, I had to be logged in to Reddit, and a password had to be saved for reddit.com. Finally I found a workaround: disabling "Automatically search for login data and highlight form fields" in Secure Login. I've sent information to authors of both extensions and I've submitted a Firefox bug report via Talkback. In the meantime, the workaround isn't a problem and Firefox is totally stable.